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September 10, 2005

Monkey Wrenches: Primates With Tools

Monkey's Using Tools - Intelligent Breakthrough or Mimicry?

You may know that chimpanzees and gorillas have been known to use tools - like reeds to suck termites out of holes and such, but routine tool usage is not common. Now, researchers have discovered another instance in a wild population of capuchins-monkeys.

BRAZIL -

Apparently capuchins—monkeys more familiar as organ grinders and in circus sideshows—are ingenious enough on their own to use crude stones for cracking palm nuts.

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The study, which was led by University of Georgia psychologist Dorothy Fragaszy, is the first to document tool-use behavior in an entire population of wild capuchins.

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"This type of tool use is a very sophisticated behavior," said Fragaszy, an expert in capuchins ... "It has never been witnessed in a group of wild monkeys before," she said. "There have been some isolated incidents, but no routine tool use in a wild population."

More at: National Science Foundation: Monkey Business

So I'm trying to wrap my head around this tool usage concept. It seems like it would be impossible to prove that the monkeys have come up with this hammering on their own versus having been trained to do it by a "more intelligent" being like a human... or even perhaps a bird like a macaw (also known to be highly intelligent). So we know the effect - monkeys using tools - and so I started conjecturing on the cause.

Possibility #1 - Training: A somewhat domesticated monkey was actively taught to do this by a human, escaped into the wild, taught all his friends.

Possibility #2 - Mimicry: A monkey watched a human or some other creature do this, mimicked it and found it worked, and taught all its friends.

Possibility #3 - Inventiveness: An industrious monkey came up with the idea all by itself, found it worked, and sent out the memo to teach all all its friends.

Possibility #4 - Accidental Brilliance: An regular monkey accidently successfully broke a nut, wow cool it worked, and thus the behavior is repeated and thus supported for the future. Almost like a random genetic trait becoming dominant because it works well and those monkeys are more likely to live than the monkeys that don't eat the nuts.

So it seems to me that any of these possibilities show that these monkeys are pretty smart - if only because the trait seems to be passed down to the next generation, but how long has this been going on, we don't know.

I think the possibility showing the least "intelligence" is probably #1 - Training - because the monkey isn't actively using the tool, although training may also involve some mimicry, which was #2. That said, mimicry occurs in the wild in lots of species which are generally not considered at the top of the intelligent species lists - like bugs, especially when trying to avoid predation or to feed oneself more effectively. Again, you've got the animals using mimicry (and camouflage) being eaten less often or to eat more often, so the trait - which might have been a random mutation to start - continues to be passed down.

Inventiveness, #3, and accidental brilliance, #4, are almost the same from our perspective, unfortunately. Their difference is basically in the KIND of intelligence - inventiveness shows a problem-solving skill whereas accidental discovery shows solution recognition and re-implementation. It would be amazing to be able to prove that the monkeys methodically went about trying to problem solve: they had a nut, when they would find broken ones, they tasted good, so the monkeys went about figuring out a way to break them open themselves. But since scientists are coming in late in the game and seeing only the results, not the initial evolution of the behavior, there's just no way we'll ever know.

Just after I originally wrote this, the story made the NSF radio/podcast Imagine That! with a cool interview you might want to catch.

Using currency is often considered one of the features of a civilized culture. Well, it didn't take long to teach monkeys to spend, spend, spend! I bet they could be taught "credit" all too easily, as well.

When it comes to shopping, capuchin monkeys act all too human. A new study from Yale University found that capuchins demonstrate the exact same rational and irrational behavior as humans when they are given the power to buy.

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Research assistants spent hours with the monkeys, training them to recognize the tokens as having a value. Once the capuchins realized that the tokens could be exchanged for treats such as grapes or apple chunks, they resorted to some very human behaviors, including stealing the tokens from other monkeys.

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In the first experiment, the monkeys were given a budget of 10 tokens and allowed to exchange those tokens for a variety of treats. Research assistants played shopkeeper, each offering a different food. As the monkeys “shopped,” researchers would change the value of the tokens. A token might be worth one grape one day but two grapes the next. Chen says that the monkeys’ reaction to price fluctuation was perfectly rational—and quite human. When prices went up for one food, the monkeys bought less of it. When prices went down, they bought more.

More at: NWF: Spend Like a Monkey

In other news, gorillas have also been known to use tools. Captive gorillas are often kept entertained with tools and such, but seeing tool usage in the wild is a lot more difficult - but it's definately there. For example, recently scientists witnessed gorillas using tools to test the depth of water as well as an industrious gorilla that moved a large tree limb across an area of water to use it as a bridge.

From their vantage point in a clearing at Mbeli Bai in the northern Republic of Congo, Breuer and his colleagues spotted a female gorilla, called Leah, studying a pond before venturing a few steps into it. She then turned back and grabbed a handy metre-long branch from the bank, which she proceeded to use as a 'walking stick', repeatedly prodding the pond's bottom with it. After apparently assessing the depth of the pond with each prod, she eventually moved almost 10 metres from the shore.

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The researchers saw another female, Efi, using the trunk of a dead shrub as a bridge to cross swampy ground. Efi ripped the 1.3-metre-long, 5-centimetre-wide section from the ground and leant on it like a crutch while she trawled the marshy ground for food. Then she laid it down like a plank and strode over it.

More at: Nature: Gorillas branch out into tool use

It's common to see trained dolphins in captivity and there are lots of sci-fi stories of dolphins being used for reconnaissance like Day Of The Dolphin. Some real dolphins also use tools in the wild. Some Australian dolphins wear sea sponges on their noses in order to protect their beaks. The sponge acts as a barrier against the rocky sea floor as well as stinging creatures which live there.

Scientists first spotted the sponging dolphins in Shark Bay 20 years ago, but they didn't know where the behavior came from. Now, a new study suggests that the dolphins don't figure out the trick on their own, nor do they inherit the ability. Instead, they learn it from their mothers.

More at: Dolphin Sponge Moms

Posted by sorsha at September 10, 2005 6:16 PM